We thus arrive at the discouraging conclusion that in a belligerent country all opinion in any way connected with the war is subject to prejudice, either pro-national or anti-national, and is very likely in consequence to be of impaired validity. Must we then conclude further that speculation upon war themes is so liable to distortion that reasoned judgments of any practical value are impossible? Now, it is guidance in just such a difficulty as this that a psychology having any pretensions to be called practical may fairly be expected to yield, and psychology does in fact provide certain broad precautionary principles, which, although by no means infallible guides, do profess to be able to keep within bounds the disturbing effects of prejudice on judgment and so render possible the not wholly unprofitable discussion even of matters the most deeply implicated by war-time passion.
First among such principles is the recognition of the fact that prejudice does not display itself as such to direct introspection. One who is being {221} influenced by prejudice will never be able to detect his biassed judgments by an apparent defect in their plausibility or by any characteristic logical weakness. Agreement or disagreement with common opinion will as such be no help, since prejudice infests minorities no less than majorities. To suppose that when one has admitted the liability to prejudice one can free oneself from it by a direct voluntary effort is a common belief and an entirely fallacious one. Such a task is far beyond the powers of the most fully instructed mind, and is not likely to be undertaken except by those who have least chance of success. Prejudice, in fact, is for the individual like the ether of the physicist, infinitely pervasive and potent, but insusceptible of direct detection; its presence is to be assumed as general, but it escapes before immediate search by introspection as the ether eludes the balance and the test-tube.
Secondly, it is possible for the investigator, having admitted the existence of prejudice as a condition of thought, to recognize the general direction